NO. \m. NEW SPECIES OF CAUaiN.E— WTLSON. 597 



the male, are very livel}^, moving about rapidly on the inside of the 

 iish's mouth, so that the}^ are difficult to catch uninjured. When 

 transferred to an aquarium they swim about as constantly and as 

 restlessly as Caligus rapax. But so far as observed neither sex man- 

 ifested any desire to crawl up out of the water like so many other 

 species. 



CALIGUS RUFUS, new species. 

 Plate T.. 



Types.— Cat. No. 32812, U. S. National Museum. 



Female. — Body elongate and narrow in all its parts; carapace 

 elliptical, considerably narrowed anteriorly and posteriorly, six- 

 elevenths of the entire length, and nearly one-half longer than wide ; 

 fi'ontal plates exceptionally wide and prominent; hmules large, 

 widely separated, and not projecting; frontal margin with a slight 

 curve and a shallow incision at the center, in which can be seen the 

 remains of the frontal filament. 



Posterior sinuses narrow, triangular, and shallow; median lobe 

 five-eighths the width of the carapace and projecting far behind 

 the lateral lobes, its sides tapering rapidly, its posterior margin 

 evenly rounded; thoracic area nearly half the entire length, with 

 a wide and squarely truncate anterior margin; eyes comparatively 

 large and situated far forward, close to the frontal plates. 



Free segment short and only half the width of the genital segment; 

 the latter oblong with straight sides and evenly rounded corners; 

 fifth legs invisible dorsally. 



Abdomen one-jointed, two-fifths as wide and two-thirds as long 

 as the genital segment, tapering considerably; anal laminae long 

 and narrow and inclined toward each other; terminal seta^ nearly 

 as long as the whole abdomen; egg strings about tlu-ee-fourths 

 as wide as the abdomen and three-fifths of the entire body length; 

 30 to 40 eggs in each string. 



Second antenna^ rather small, tlu'ee-jointed, the basal joint carry- 

 ing a large spine on its ventral surface, the terminal claw stout and 

 strongly curved; first maxilhe small and rudimentary, consisting 

 principally of a swollen l)ase on which are borne two papillfe, each 

 tipped with two seta% in addition to the short, slender, and nearly 

 straight terminal portion. 



Second maxilhv slender and elongate, with a triangular base carry- 

 ing on its anterior corner a large papilla armed with two setae. These 

 maxilhv curve outward slightly and reach nearly to the end of the 

 mouth tube. 



This latter, the mouth tube, is of an unusual pattern for the 

 Caligime and resembles that found among the Pandarime more 

 than in any species thus far described. It is narrow and fulh' four 



